Detachably locking device for circuit interrupter



United States Patent [111 3,546,41 1

[72] Inventor Yoshlo Kobayshi [S 6] References Cited 2] A I N ggagillpcn UNITED STATES PATENTS f D8313, 1968 3,474,206 10/1969 Gryctko ..200/l68(A)UX [45] Patented Dec. 8, 1970 Primary Examiner-H. 0. Jones [73] Assignee Terasald Denki Sangyo Kabushiki Kaisha """y Lind & lack Osaka, Japan v [32] Priority Dec. 26, 1967 [33] Japan v i 108,202 ABSTRACT: A plug-in-type circuit interrupter is plugged into two terminal blocks connected to opposite ends of a bus line. One bolt planted between each pair of terminals on each [54] gfi g fi g o DEVICE FOR CIRCUIT block extends through and projects beyond a through hole 3 Chins 3 Drawin g formed in the interrupter. One cap nut is screwed onto the g projecting portion of each nut to lock the interrupter to the [52] U.S.Cl. 200/168, terminal blocks. When the nut is being unscrewed it exerts 317/! 19 upon the interrupter a force tending'to separate the inter- [Sl] lnt.Cl ..l H0lh 9/08 rupter from thesblocks until it is ready for being manually [50] Field of Search ..200/168(A); removed from the blocks. The nuts are retained in the inter- Q 317/1 18, l 19 rupter so as to fall out from the latter PMENIEMEB slam 1. 5 1 1 sum 1 OF 2 FIGJ INVEN'I'OR YOSHIO KOBAYASHI Y 0 I j [1/ 1 M/zd 3,41%.(203

ATTORNE Y5 DETACIIABLY LOCKING DEVICE FOR CIRCUIT "INTERRUPT ER BACKGROUND OF THE INVENTION This invention relates to a device for detachably locking a plug-in-type circuit interrupter to terminal block.

In order to ensure thataplug-in circuit interrupter plugged into the associated terminal blocks connected to a bus line is electrically connected to the source and load sides of thebus line, it is required to provide a high contact pressure under which the male terminals -of the interrupter contact the respective female terminals of the blocks. If such a circuit interrupter becomes higher in current-carrying capability then it is necessary to use a locking device to couple the main body of the interrupter to the associated terminal blocks in order to ensure that the interrupter is maintained plugged into the blocks. n the other hand, if the interrupter is in plug-in relationship with the terminal blocks under a high contact pressure then it is difficult to manually pull the interrupter out from the terminal blocks after the locking device has been released. The larger the dimension of the interrupter the greater will be this dIffiCUIty. This inevitably leads to a screwdriver being used to pry the interrupter separated from the terminal blocks with the result that a molded housing for the circuit interrupter and/or the associated terminal blocks may sometimes damage.

SUMMARY OF Tire INVENTION Accordingly it is an object of theinvention to provide a new and improved device for easily locking a plug-in-type circuit interrupter to the associated terminal block or blocks'while making it possible to readily disengage the locked interrupter from the terminal block or blocks with no damage to either or both of the interrupter and block or blocks.

With this object in view, the invention resides in a detachable locking device comprising a circuit interrupter, a terminal block into which the circuit interrupter is adapted to be plugged, a bolt member planted on the terminal block to extend in a direction in which thecircuit interrupter is plugged intotheterminal block, a through hole disposed in the circuit interrupter, the bolt member extending through and projecting beyond the through holes when the circuit interrupter is plugged into'the terminal block, and a nut member engaging the projecting portion of thebolt member to lock the interrupter to the terminal block, the nut member being always retained in the circuit interrupter to be rotatable about the axis of the bolt member as well as beingmovable axially of the bolt member to a limited extent.

BRIEF DESCRIPTION OF THE DRAWING shown in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the invention will now be described in terms of a three-pole circuit interrupter it is to be understood that it is equally applicable to circuit interrupters having any. desired number of poles.

Referring now to the'drawings and in particular to FIG. I there is shown a three-pole circuit interrupter generally designated by the reference numeral comprising a closed enclosure including a housing 12 and cover member 14 detachably connected togetherjnto a unitary structure. The housing and. cover member I-i"- and 14 respectively may be fonned of any suitable electrically insulating material by the molding technique. The interrupter 10 comprises, in addition to the conventional components for conducting the switching one for each'poledisposed inspacd-parallel relationship in the directionnormalto the plane of Flfial on each of opposed end portionsofthebottom of the housing 12 and projecting beyond the bottom. Although one of terminals 16 is illustrated only on the left-hand endportion as viewed in FIG. 1 of the interrupter it will be apparent that the identical terminals are similarly disposed on the right-hand end portion of the interrupter.

A female terminal block generally designated by the reference numeral 18 is electrically coupled to an electrical equipment to: be connected, in this case, to a bus line representedbythe reference character A and includes a plurality of tulip shaped contacts B, one for each pole disposed in the same manner-as arethemale terminals l6and within individual recesses formed'in the terminal blocks 18. The contacts-B are connected to ithe'respeotive phase conductors of the bus line A. It is to be understood that the tulip shaped contacts B are disposed in'such positions that they receive the respective male terminals 16 of the interrupter as plugged into the terminal blocks 18, While the contacts B are shown in FIG. 1 asbeingpositionedin the'left-hand terminal block it is to be understood that similar contacts are also included in a female terminal block 18 of the same construction as illustrated in the right-hand portion of FIG. 1.

As shown in FIG. 1, the contact B includes a terminal bolt 20 extended. and sealed through the bottom of the individual recess of the block 18and having a reduced head portion, and a plurality, forexample, four of contact fingers 22 of any suitable resilient materialhavi'ng one end firmly secured to the reduced bolt head portion by .a resilient ring 24 disposed around the latterportion to fasten'the'tingers to the bolthead portion. The other or free ends of the contact fingers 22 are constrained by another resilient ring 26 so that the contact fingers 22 are formed into a tulip shape. Each set of contact fingers 22 is adapted to permit the associated plug type terminal 16 of the interrupter to'be'readily. inserted thereinto and held in contact therewith under a predetermined contact pressure.

:Theterminal bolt 20 is connected to a corresponding one of the phase conductors of the bus line A.

According to the teachings of the invention one detachably locking device generally designated by the reference characterC is disposed between each pair of adjacent tulip shaped contactsB -of..each terminal block 18 and between each pair of the corresponding male terminals 16 of the interrupter10. -As best'shown -in FIG; 3, the locking device C includes one'mounting bolt 28xplanted on the terminal block 18 between each pair of adjacent contacts B to extend in a direction inwhich' the interrupter'lO is plugged into the terminalblocks l8 and having an electrically insulating layer 28a disposed onto that portion thereof adjacent'the block 18.

On thetother hand; the housing 12 is provided with one stepped through hole 30 through which the corresponding one of the mounting bolts-28 on the-terminal block 18 is adapted to extend upon plugging the interrupter into the terminal blocks. The through hole '30 includes a lower portion 30a larger in diameter than the intermediate portion thereof to 'receive the insulated-bolt portion 28a and an upper portion also larger 'in'diameter than the intermediate portion thereof. Upon plugging the interrupter 10 into each of the terminal blocks 18, the'bolts 28 are adapted to project into the upper hole portion 30b. A cap nut 32 is disposed in each of the upper hole portions 30b and adapted to engage the projecting portion of the bolt 28 with a washer and a spring washer interposed aroundthe projecting bolt portion between the cap nut 32 and the bottom of the upper hole portion 30b. The cap nut 32 is'provided on the headwith a hexagonal or square depression 34 for the purpose-as will-be apparent hereinafter. The

upper hole portion 30b is dimensioned such that the cap nut 32 is rotatable about the axis of the bolt 28 and along with a washer 36 disposed thereupon movable axially of the bolts to a limited extent for the purpose as will be also apparent later.

The cover member 14 is provided with a mounting through hole 38 alined with each of the upper hole portions 30!). The hole 38 has a diameter sufficient to prevent the washer 36, the cap nut 32 etc. from falling out from the correspondinghole portion 30b.

The circuit interrupter can be put in electrical contact with the bus line A by having its terminals 16 fitted into the corresponding tulip shaped contacts B on both the terminal blocks 18. Under these circumstances the free end portion of each bolt 28 extends into the corresponding hole portion 30b as above described. With the cover member 14 removed, the cap nuts 32 are caused to engage the respective bolts 28 with the above-mentioned washer and spring washer interposed between each of the nut and the bottom of the associated hole portion 30b around the bolt. Then the cover member 14 is rigidly secured to the housing 12 after which an operating tool such as a screw driver having a head complemental in shape to the depression 34 on the nut is inserted into one of the mounting hole 38 in the cover member 14 until its head is extended through the washer 36 and fitted into the depression 34. Then the tool is operated to screw the cap nut 32 onto the bolt 28. The process just described is repeated for the other cap nuts until the interrupter 10 is locked to the terminal blocks 18 and therefore the bus line A. FIG; 1 shows the interrupter after having been locked to the terminal blocks.

If it is desired to removal the circuit interrupter Whom the terminal blocks 18 the operating tool previously used can be successively inserted into the mounting holes 38 to release the respective cap nuts 32 from the associated bolts 28. In this process, the cap nuts 32 engage the bottom of the cover member 14 through the respective washers 36. A further release of each cap nut causes the housing 12 integral with the cover member 14 to be gradually raised from the terminal block 18 until the plug-type terminals 16 are separated away from the associated set of the contact fingers 22 as shown in FIG. 2. Under these circumstances the interrupter can readily be separated from the terminal blocks.

From the foregoing it will be appreciated that the plug-intype circuit interrupter can be easily locked to the female ter minal blocks only through the rotational movement in one direction of the cap nuts 32 around the associated mounting bolt 28. Also if it is desired to remove the interrupter from the terminal blocks, it is required only to rotate the cap nuts in the opposite direction to release them from the associated bolts.

until the interrupter is raised from the terminal blocks by the action of a force tending to pull the male terminals of the interrupter out from the associated tulip shaped contacts of the terminal blocks. Thus the interrupter is ready for manually pulling the interrupter out the blocks. Also since each hole 38 in the cover member 14 is smaller in diameter than the alined hole portion 30b formed in the housing each cap nut is always disposed in the enlarged hole portion 3012 resulting in no fear that the cap nuts are lost.

While the invention has been illustrated and described in conjunction with a single preferred embodiment thereof it is to be understood that various changes in the details of construction and the combination and arrangement of parts without departing from the'spirit and scope of the invention.

1 claim:

1. In a device for detachably locking a circuit interrupter to a terminal block, the circuit interrupter being adapted to be electrically coupled to the terminal block through a plug-in connection, the combination of a bolt member planted on said terminal block to extend in a direction in which the circuit interrupter is plugged into the terminal block, a through hole disposed in said circuit interrupter, said bolt member extending through and projecting beyond said through holes when the circuit interrupter is plugged into the terminal block, and a nut member engaging said bolt member locking the circuit interrupter to the terminal block, said nut member being always retained in the circuit interrupter to be rotatable about the axis of the bolt member as well as being movable axially of the bolt member to a limited extent.

2. A detachable locking device as claimed in claim 1 wherein said nut member is adapted to be unscrewed whereby said circuit interrupter is pulled out from said terminal block.

3. A detachable locking device as claimed in claim 1 wherein said nut member is adapted to be unscrewed whereby said plug-in connection through which the circuit interrupter is electrically coupled to the terminal block is broken. 

